How to identify last item in a nested .Net Repeater

If you have a typical Orders/Products page and you want to show every product inside every order I think the best solution is to use a Repeater (of products) inside a parent Repeater (of orders).

If you must do something in the last product template of a order how can you reach this condition?
In the OnItemDataBound of a nested Repeater you can count his DataSource casting it to the item collection type; for example: